The objective of the thesis is to analyze optical transport network architectures in terms of their ability to survive failures. Architectures are classified according to three paradigms; switching, topological and protection and restoration. The thesis proposes optical network architecture based on the premise that the provisioning of the fundamental service classes, circuit and packet switched, will be moved to the optical layer. Generic node structure for the proposed optical network architecture is presented with its functional elements and interfaces. The thesis presents generic availability modeling procedure that consist of modeling of an optical network and its corresponding transport entities, and creating of related availability structure. Further on, availability calculation techniques, analytical and simulation are used to evaluate availability performance. The procedure takes also into account complex dependencies between network entities failures. Availability models for optical circuit and packet switching paradigms are presented. Design procedures are used to create model of optical transport network. Procedures are based on the application of generic heuristic search techniques, such as Genetic Algorithms, Simulated Annealing and Tabu Search. The thesis describes object orient framework Nyx aimed at fast creation of design and optimization procedures. The thesis presents in detail an application of the Nyx to the design of a network employing p-cycle topological paradigm. The presented availability modeling procedures are applied in the availability analysis. COST 266 case study topologies are used. Results for the optical circuit switched, mesh and p-cycle, and packet switched architectures are presented. Sensitivity analysis of the availability for the circuit and packet switched architectures is performed.